<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

<input type="text" placeholder="半径" id="r">
<input type="text" placeholder="周长" id="c">
<input type="text" placeholder="面积" id="s">




<script src="js/script.js"></script>
</body>
</html>